Measurement of the $B_c^{+}$ meson lifetime using $B_c^{+}\to J\text{\hspace{0.17em}⁣}\mathrm{/}\text{\hspace{0.17em}⁣}\psi {\mu }^{+}{\nu }_{\mu }X$ decays

The lifetime of the $B_c^{+}$ meson is measured using semileptonic decays having a $J\text{\hspace{0.17em}⁣}\mathrm{/}\text{\hspace{0.17em}⁣}\psi$ meson and a muon in the final state. The data, corresponding to an integrated luminosity of $2\mathrm{f}{\mathrm{b}}^{-1}$, are collected by the LHCb detector in $pp$ collisions at a centre-of-mass energy of $8\mathrm{T}\mathrm{e}\mathrm{V}$. The measured lifetime is $$\tau =509\pm 8\pm 12\mathrm{f}\mathrm{s},$$ where the first uncertainty is statistical and the second is systematic.